1. Field of the Invention
The present invention relates to fluid regulators of the type which typically reduce a high fluid pressure to a lower downstream pressure suitable for operating fluid-driven tools or equipment. More particularly, the present invention relates to a relieving-type fluid regulator which allows high fluid pressure to be vented from the regulator if the regulator seal should leak.
2. Description of the Background
Fluid regulators are used in various industries to controllably regulate downstream fluid pressure to equipment or tools powered from a relatively high pressure fluid line. Pneumatic regulators are generally classified as being either of the non-relieving or the relieving type. In the former case, the user is generally not concerned with detecting regulator failure, and may not want the regulator to continually vent high pressure if the regulator seal should fail. A non-relieving regulator is thus commonly used in an assembly facility to operate a pneumatically driven motor. If the regulator seal fails, a diaphragm within the regulator typically ruptures and high pressure fluid will briefly be vented to the atmosphere, causing the regulator to at least substantially restrict further fluid flow past the regulator. The operator of the drill motor readily observes this condition, turns off the valve upstream of the regulator, and replaces the regulator.
In a non-relieving regulator, a leak of the regulator valve allows the high pressure fluid to intentionally leak from the regulator rather than blowing out the regulator diaphragm, thereby allowing the regulator to continue operation at approximately the originally set pressure. Accordingly, this type of regulator has a significantly reduced failure rate, and is frequently used in situations where one is not primarily concerned if high pressure fluid vents from the regulator, but rather is primarily concerned that low pressure fluid will continue to be supplied to a downstream tool or equipment even if the regulator seal fails. A relieving type regulator may thus be employed to supply reduced pressure to a sampling pump which is infrequently checked by an operator. It is critical to the operation of the sampling system that low pressure fluid continue to be available to operate the sampling pump even if the regulator seal fails, and a relieving-type regulator satisfies this requirement.
A non-relieving regulator may be easily adjusted to increase the downstream pressure, for example from 50 psi to 60 psi, although a non-relieving regulator typically cannot be easily adjusted to decrease the downstream pressure, e.g. from 60 psi to 50 psi. In order to adequately lower the downstream pressure, an operator must let that air out or otherwise partially bleed the system downstream from the regulator. In a relieving regulator, an operator can either increase or decrease the downstream pressure without otherwise bleeding air from the downstream system.
A significant problem with prior art relieving-type regulators concerns their generally poor sensitivity. Regulator sensitivity is generally defined as the ability of a regulator to incrementally control downstream pressure, coupled with its ability to maintain the set downstream pressure with a change in the high pressure supplied to the regulator. Prior art regulators generally suffer from poor sensitivity in that an operator is not able to incrementally adjust the downstream pressure, e.g. from 50 psi to 52 psi, and the adjusted downstream pressure of 52 psi cannot be continually maintained at that level if the upstream pressure varies from 1,000 psi to 1,200 psi. In order to allow such fluid regulators to be sufficiently sensitive, the effective diameter of the regulator diaphragm conventionally is closely maximized compared with the diameter of the valve member or dart which seals with the regulator seat. Moreover, the surface finishes for components of prior art relieving-type regulators is critical, and thus the regulators are expensive to manufacture and costly to maintain. An exemplary prior art relieving-type air regulator is available under Part No. 30-0100 from YZ Industries.
The disadvantages of the prior art are overcome by the present invention, and an improved relieving-type fluid regulator is hereinafter disclosed which may be inexpensively manufactured and maintained compared to prior art relieving-type regulators.